Sallaz polishing is a substrate preparation technique for exterior parts, which MINASE excels at. MINASE successfully provides distortion-free surfaces and sharp edges to the exterior of our watches by utilizing over 30 years of experience in applying sallaz polishing to the cases of high-quality watches. There are only a few manufacturers that apply sallaz polishing even to indices on dial plates, let alone most surfaces of the case. It is time-consuming, but produces an excellent finish.
To apply sallaz polishing, we attach abrasive paper to a rotary disk, then use the disk to polish the cases and indices. We seek to minimize distortion in exterior parts, and so the cases are repeatedly forged to prevent pinholes from appearing on the surface. Then, sallaz polishing is applied to make the surface completely smooth. Finally, the sallaz-polished surfaces are usually buff-polished to completion.
One of the features of MINASE watches is the hands, which proceed as if crawling over the dial plate. The clearance between the dial plate and the lower hand is only 0.3 mm, between hands, 0.3 mm, and between the upper hand and the glass, 0.5 mm. Even a slight fault will degrade the appearance and may even cause the watch to stop. To provide accurate clearances as designed, our craftsmen adjust the bending of hands one by one and assemble them carefully.
This shows the manufacturing of a bracelet segment of HiZ DIVIDO. Bracelet segments are normally manufactured by pressing and polishing sheet materials. Nevertheless, we developed a new manufacturing method to create even more precise bracelets. In our method, segments are extracted from a metal block one by one by means of wire electric discharge machining. Then, the segments are carefully ground one by one by craftsmen to ensure the correct, consistent clearance between the segments. The required accuracy is of the order of 1/100 mm. Such high accuracy results in the delicate feel of MINASE’s bracelets, which is unique to high-quality watches. MINASE still uses the manufacturing method once found in ultrahigh-quality bracelets.
This movement is uniquely customized by MINASE. MINASE’s craftsmen apply perlage finishing to the entire surface of ETA’s movement. Perlage finishing, which creates pearly patterns on the workpiece, is normally applied to just a small area in view of the cost. And yet MINASE applies it to as large an area as possible to deliver a truly beautiful appearance and to enhance the contrast with the luster of the case. Perlage finishing grinds the surface of workpiece and consequently removes the original silver plating, and so we apply silver plating again to perlage-finished parts. We create such a beautiful finish that no one can notice that it is re-finished.
This photo shows the forging of cases, which MINASE excels at. Forging is often used as a way to manufacture cases at low cost, but MINASE repeatedly forges the cases in order to harden the material and improve the endurance. The materials are hardened by repeated forging, so MINASE performs forging at least 10 times when preparing the cases. Every forging is followed by annealing at 1,100°C or higher for 20 to 25 minutes to eliminate distortion. We take pride in making every effort.